Cumulus Support

There really needs to be a sub-forum for all the posts relating to people moving from Cumulus 1 to Cumulus MX.

This topic viewtopic.php?f=39&t=13298 was set up to record what was in Cumulus 1 but has not yet been implemented in MX. That is probably greatly out of date now, but maybe somebody wants to work through that topic and add items still outstanding to this new topic.

If the new sub-forum was created, it could collect together all the questions and answers on that issue.

It would also help those contemplating moving if there was somewhere to look up the differences between the two flavours.

Some of the posts just referenced talk about additional features available in MX, and I have tried to capture some of that in Wiki articles; but nowhere at the moment summarises what is in Cumulus 1, but not in MX.

If Steve Loft had a list, I can't find where it was shared. If Mark has a list, again it has not been shared. There is a lot of commented out code in the MX source files, but I can't be sure "which bits are obsolete" and "which bits not yet implemented" as there is no annotation to help me. Consequently, my research has failed to find a definitive list.

The rest of my post where I made a start on defining what features in Cumulus 1 have been rejected for inclusion in MX, has been deleted, because subsequent posts in this topic are all purely MX related and ignored the earlier subject, and ignored which sub forum this was posted in!
I'm now recording C1/MX differences in Wiki in a new article there, that is less likely to be mucked up by others. Administrators can delete this post and all subsequent ones as far as I am concerned.

to find your port (usb) use the following method I posted many moons ago.

viewtopic.php?p=122240#p122240

The original content has been moved to Wiki

This topic has been hijacked, by several MX specific posts, so I have had to change the topic subject from the one shown for this post and move the contents to where people might find them.

Just a minor one from me, the days since last rain counter.

Just a minor one from me, the days since last rain counter.

There are the following tags which relate to your comment:-
ConsecutiveDryDays
ConsecutiveRainDays
MinutesSinceLastRainTip

This post was about issues you might encounter if you decided to stop using Cumulus 1.

sfws wrote: ↑Sun 14 Jun 2020 8:23 am Cumulus 1 and MX use different calculations for dew point - see the Cumulus 1 method (copying Davis) commented out in this code extract from https://github.com/cumulusmx/CumulusMX/ ... eteoLib.cs

Code: Select all

public static double DewPoint(double tempC, double humidity)
        {
            //return tempC + ((0.13*tempC) + 13.6)*Math.Log(humidity/100.0);
            // Davis algorithm
            double lnVapor = Math.Log(ActualVapourPressure(tempC, (int) humidity));
            return ((243.12 * lnVapor) - 440.1) / (19.43 - lnVapor);
        }

This replacement is NOT as per dew point calculation in e.g. wikipedia (you can find a JavaScript version of that at https://github.com/nicolasgrancher/wea ... eather.js

The Dew Point calculation MX uses is the Davis algorithm (the commented out line of code above is incomplete) - which Davis say is "an approximation of the Goff & Gratch equation". This is functionally identical to the Magnus formula using the Sonntag 1990 values for the SVP constants. This is current widely used approximation for dew point.

I do not know how Cumulus 1 calculated dew point as I have to access to the source.

sfws wrote: ↑Sun 14 Jun 2020 10:02 pm Cumulus 1 and Cumulus MX use different water vapour pressure formula for Canadian Humidex, that only appears in current conditions. So, like dew point in my previous post, there will be a discontinuity if you choose to move from Cumulus 1 to MX.

Humidex can be calculated from temperature and humidity in every line recorded in standard log file, so if you have enough skill you can calculate highest and lowest for day, week, month, year, and indeed all-time, but Cumulus will not do these calculations for you.

What calculation did Cumulus 1 use for SVP?
I have no access to the source code so cannot determine it. I have looked at the various SVP calculations and the differences are normally small, for instance contributing only 0.1C difference at 30C for the Feels Like calculation (less than 0.1 below 30C).

sfws wrote: ↑Sun 14 Jun 2020 10:02 pm Cumulus 1 and Cumulus MX use different formulas for wind chill. So, like dew point in my previous post, there will be a discontinuity if you choose to move from Cumulus 1 to MX.

Ditto my comments on Humidex.
MX uses the current Wind Chill calculation.

sfws wrote: ↑Sun 14 Jun 2020 10:02 pm Cumulus 1 and Cumulus MX use different formulas for USA Heat Index. So, like dew point in my previous post, there will be a discontinuity if you choose to move from Cumulus 1 to MX.

Ditto my comments on Humidex.
MX uses the NOAA calculation - https://www.wpc.ncep.noaa.gov/html/heat ... tion.shtml

I believe it is worth making a record that such differences for dew point, humidex, and other Cumulus 1 derivatives exist, and that a discontinuity exists if someone contemplates a move to MX, remember there are still plenty of people using Cumulus 1, and of course many who have more years of C1 measurements than years of MX measurements.

Steve Loft stated the formulas he used for each value in C1 either in C1 FAQ or in response to forum questions.
He used a variety of sources, and I don't know how he made decisions on selection, it might be he picked the first one appearing in a search engine. I suggest that because a few came from wikipedia rather than "official" sources.

Any further discussion on calculations done by Cumulus 1 will have to continue elsewhere, this topic has been hijacked to discuss purely MX issues.

Ok, I just didn't want people to think they would see big differences in the figures between C1 and MX

Well it seems to me there is a big difference!

Feels like used to track well above Apparent previously But now it is tracking well below Apparent

Just a colour switch?
You left out the interesting part of the legend

No colour switch.
You can see the beginning and end of "Apparent".
The traces are the same colour for the same values in both images.
There is no significant part of the image missing.

This is also what I see on the blocks on the MXUI website where I currently have Feels like lower than Apparent which always used to be the other way around.
If you want better answer then your cryptic comment needs to be much less cryptic!

BCJKiwi wrote: ↑Sat 20 Jun 2020 8:00 am Well it seems to me there is a big difference!

Feels like used to track well above Apparent previously
Feelslike3079.PNG

But now it is tracking well below Apparent
Feelslike3084.PNG

There is no temperature scale on the first image, so it is impossible to make any comparison. We also need the corresponding wind speeds and humidity values. Without all the variables used the comparison is not meaningful.